Jul. 29, 2011

Throughout history, humans have enjoyed a very comfortable climate on Earth, due to the naturally occurring greenhouse effect. So, c’mon kids! Let’s review the greenhouse effect! (Maybe if we ACT like it’s fun, it WILL be. Fake it ’til you make it, right?)

Sunlight enters our atmosphere passing through stuff that includes molecules of methane, Nitrous oxide, water vapor and carbon dioxide (CO2), which are known as “greenhouse gases.”

When it reaches Earth, some sunlight (now we’re talking “visible light” specifically) hits things that are very reflective — like ice and snow. This sends the light right back out to space.

As the light leaves the atmosphere, it passes right through the greenhouse gases, just as it it did when it entered the atmosphere. Those darned greenhouse gases STILL don’t care.

However, some visible light coming from the Sun hits the Earth’s absorbent surfaces, like soil and water. Those surfaces soak up the light’s energy, which makes the surfaces warmer.

After a while the warm, absorbent surfaces start radiating the heat back out, only now the heat is emitted in the form of infrared waves.

On their way out of the atmosphere, the infrared waves pass through the greenhouse gases. Some waves head out to space uncontested, but some waves make contact with the gases, which react with the waves: the gases absorb them.

The greenhouse gases molecules absorb the waves’ energy and, as the Earth did earlier in the process, they eventually start radiating the waves (heat) back out in all directions. Some waves head out to space, and some head back into the atmosphere.

As a result, the atmosphere is warm. Warm enough to make Earth a perfect climate for life. It’s this act of keeping heat contained in our atmosphere that prompted the term “greenhouse.”

Without the greenhouse effect, it’s estimated Earth’s average temperature would be 50 degrees colder. Keep in mind a mere ten degrees would bring about an ice age, so 50 is BIG TIME.

With the industrial revolution, humans began burning a lot of stuff, releasing various elements — most notably CO2, a long-lasting greenhouse gas.

With an increased amount of greenhouse gases in the atmosphere, more infrared rays was getting absorbed and, as a result, more heat was being kept in the atmosphere. It’s kind of like replacing a large-holed sieve with one made of a fine mesh; you trap more stuff.

One final kicker: the increased heat in our climate causes a ton of chain reactions, such as the warming of permafrost which — when melting — releases (you guessed it) MORE greenhouse gases!

Your creative idea could be chosen to appear in the September 23rd edition of What on Earth? which highlights Moving Planet, the worldwide event being planned by Bill McKibben’s 350.org environmental organization. Entering the contest is easy: